Conventional treatments of skin disorders typically involves the topical application to affected areas of hydrating emollient or moisturizer compositions including an active agent of choice, an example of which is an alphahydroxy acid (AHA) such as glycolic acid and the like. Compositions of this type are described in U.S. Pat. Nos. 3,879,537; 3,920,835; 3,920,840; 3,984,566; 3,988,470; 4,021,572; 4,104,782; 4,105,783; 4,197,316; 4,234,599; 4,246,261; 4,363,815; and 4,380,549.
In the treatment of certain skin conditions with such compositions which ordinarily have a pH of about 2 or less, it was found the compositions undesirably caused some skin irritation with redness and sensation of burning. One solution which was offered to avoid this problem was to lower the concentration of the hydroxy acid in the composition. Another solution was to partially or wholly neutralize the hydroxy acid with a base such as ammonium hydroxide, in order to raise the pH from below 2 to near pH 4. However, these neutralization methods make the product ineffective (see Dermatology Times, May 1992). Furthermore, the use of AHA as a skin treatment for such disorders as dry skin, dermatosis, acne, keratosis, photo-aging, melasma, itching, inflammation and facial or razor bumps requires a preliminary step of applying a degreaser to the skin to remove the skin oils therefrom. Applying prior art AHA compositions to the degreased skin has the further disadvantage of delivering the therapeutic agent rapidly, and often unevenly to the surface of the skin. Results from such treatment can be less than satisfactory.
Accordingly, there is need for acceptable AHA-based compositions and treatments which eliminate the need for the separate degreasing step. There is also a need for such compositions and treatments which deliver the therapeutic agent in a more uniform, time-controlled manner. The present invention contemplates novel pharmaceutically and cosmetically AHA and AHA-like compositions which may be used in a one-step process both to degrease and treat the skin, while at the same time providing for time release of the therapeutic agent.